Myomalacia

MYOMALACIA, myomalacia (from Greek mys - muscle and malakia - weakness, softness), softening of muscles, a term, strictly speaking, applicable to all cases of a corresponding change in the consistency of muscles, both striated and smooth, but in practice used almost exclusively in relation to the heart muscle, apparently due to the fact that Ziegler, who first proposed this name (1880), characterized with it precisely changes in the myocardium (myomalacia cordis). At the core of myomalacia always lies either necrosis or at least deep degenerative changes in muscle tissue (waxy degeneration, severe degrees of fatty and hydropic degeneration bordering on necrosis) with subsequent infiltration by edematous fluid or lymph. The actual softening becomes noticeable precisely in this somewhat later period, characterized by serous infiltration of the affected area, swelling of muscle fibers, leukocytic infiltration of the tissue, and the beginning of enzymatic dissolution of the dead parts. Often this period is accompanied by hemorrhages or even hemorrhagic infarction of the entire focus. As the lytic process intensifies, the softening becomes more palpable and sharp, and subsequently, due to the development of connective tissue in place of the necrotic fibers, it is gradually replaced by induration (sclerosis). As the most frequent examples of such changes, the following can be cited. 1. In relation to smooth muscles: a) softening of the muscular wall of the intestines during their strangulation or during the development of an infarct in them due to blockage of the mesenteric artery; b) focal softening of tissue in uterine myomas on the basis of fatty degeneration, edematous infiltration, and necrosis of muscle fibers, occurring especially often during pregnancy and in the postpartum period; subsequently, in place of these foci, due to complete dissolution and decay of cells, for the most part, even cavities with liquid contents are formed. 2. In relation to striated skeletal muscles: a) softening due to waxy degeneration (see). 3. In relation to the heart muscle - see Angina pectoris, pathological anatomy. To the category of myomalacic changes, one should, in essence, also attribute those changes that occur in any muscle tissue during its purulent melting.

MYONEMES, contractile fibrils found in some protists (ciliates, gregarines, radiolarians, flagellates) that possess the ability for differentiated contraction of the body. Myonemes consist of a column of liquid contractile plasma (kinoplasm) covered by an elastic membrane. Myonemes often pass through special canals that possess their own walls.